System and method for reducing spurious emissions in a wireless communication device including a testing apparatus

Abstract

A wireless communication device is disclosed wherein isolation buffers couple to respective active circuits or stages of the device to convey test information regarding such active circuits to a test data line from which status information may be collected. The communication device operates in two modes, namely a normal operational mode wherein the isolation buffers effectively short spurious emissions from the active circuits to a ground, and a test mode wherein the isolation buffers may convey test information from a selected active circuit to the test data line. The isolation buffers prevent spurious emissions from escaping the active circuits to which they are coupled and prevent spurious emissions from traveling from active circuit to active circuit over the test data line throughout the wireless device.

1. A method of operating a wireless communication device including a plurality of active circuits comprising: operating the device in a normal mode wherein a first switch in a sensing circuit of a particular active circuit opens to decouple the sensing circuit from a test data line and wherein a second switch in an isolation buffer that couples the sensing circuit to the test data line closes to effectively short spurious radiations from the active circuit to ground, the opening of the first switch and closing of the second switch being in response to a control signal on a control bus that selects the particular active circuit from the plurality of active circuits; and operating the device in a test mode wherein the first switch closes to couple the sensing circuit to the isolation buffer and wherein the second switch opens to allow a test signal to pass from the sensing circuit through the isolation buffer to the test data line, the closing of the first switch and opening of the second switch being in response to the control signal on the control bus that selects the particular active circuit from the plurality of active circuits. 
   
   
     2. The method of  claim 1 , further comprising sensing, by the sensing circuit, an operating parameter of the active circuit, and providing the operating parameter thus sensed in the test signal. 
   
   
     3. The method of  claim 1 , further comprising instructing, by a controller, the device to enter the normal mode. 
   
   
     4. The method of  claim 1 , further comprising instructing, by a controller, the device to enter the test mode. 
   
   
     5. The method of  claim 1 , further comprising actuating, by a controller, the second switch in the isolation buffer to close to conduct spurious emissions from the active circuit to ground when the active circuit enters the normal mode. 
   
   
     6. The method of  claim 5 , further comprising actuating, by the controller, the second switch to open to permit the test signal from the sensing circuit to flow through the isolation buffer to the test data line when the active circuit enters the test mode. 
   
   
     7. A wireless communication device comprising: a plurality of active circuits including a first active circuit having a first sensing circuit that senses an operational parameter of the first active circuit; a test data line; a first isolation buffer coupling the first sensing circuit to the test data line; a control bus coupled to the plurality of active circuits; and a controller, coupled to the control bus, the controller generating a control signal that selects the first active circuit from the plurality of active circuits and instructs the device to operate in a normal mode wherein a first switch in the first sensing circuit opens to decouple the first sensing circuit from the test data line and wherein a second switch in the first isolation buffer closes to effectively short spurious radiations from the first active circuit to ground, wherein the controller further instructs the device to operate in a test mode in which the first switch closes to couple the first sensing circuit to the first isolation buffer and in which the second switch opens to allow a test signal to pass from the first sensing circuit through the first isolation buffer to the test data line. 
   
   
     8. The wireless communication device of  claim 7 , wherein the plurality of active circuits includes a second active circuit including a second sensing circuit coupled by a second isolation buffer to the test data line, the controller being coupled to both the first active circuit and the second active circuit, wherein the controller instructs one of the first and second active circuits to enter the test mode thus designating a selected active circuit while a remaining one of the first and second active circuits remains in the normal mode. 
   
   
     9. The wireless communication device of  claim 7 , wherein the first active circuit is one of a transmitter active circuit, a receiver active circuit and a baseband active circuit.